Two persons - an Indian Navy sailor and a civilian - died and two others were hospitalised when toxic gas leaked during maintenance work on the INS Vikramaditya aircraft carrier at Karwar in Karnataka, a defence spokesperson said here late on Friday.Two others who inhaled the gas are stable, officials said. The Indian Navy has ordered an inquiry into the incident. According to the navy, the incident took place at about 5 p.m. on Friday while the ship was undergoing maintenance repairs at Karwar. Maintenance work was being undertaken in the Sewage Treatment Plant (STP) Compartment. Due to inhaling toxic gas, four persons, including two sailors and two civilian workers, were evacuated to the Naval Hospital at Karwar. Two of them -- Shipwright Artificer Class 4, Rakesh Kumar and Mohandas Kolambkar, an employee of Royal Marine -- succumbed to gas inhalation. "The next of kin of the deceased have been informed. The condition of the other two personnel is stable," a navy officer said.